JOURNAL OF MEMBRANE SCIENCE
·
2010
·
IF 3.203
Zhou Hong,Chun Zhang,Xuehong Gu,Wanqin Jin,Nanping Xu
In this paper, we proposed a simple method with hydrolysis of silanes to heal nonzeolitic pores of pure silica MFI (silicalite) zeolite membranes. Three silane precursors, tetraethoxysilane (TEOS), tetramethoxysilane (TMOS) and dimethoxydimethylsilane (DMDS) were used for membrane modification at room temperature. The modified membranes were evaluated by the separation of p-/o-xylene mixture. It was found that the hydrolysis of silanes in nonzeolitic pores could obviously improve separation performance of the MFI zeolite membranes. The modification results of nonzeolitic pores were related to the silane precursors with different physical–chemical properties and molecular kinetic diameter. Compared with TEOS and TMOS, DMDS was more suitable as a precursor for healing nonzeolitic pores. For a zeolite membrane after DMDS modification, p-/o-xylene separation factor could be increased from 2.34 to 10.84 while p-xylene flux decreased only about 12.6%.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2020
·Vol. 99
·期 2
·458-466
·
IF 1.687
Xingang Li,Chenggong Zheng,Zeli Wang,Hong Sui,Lin He
The key step for the adsorption-desorption engineering process is the reversible in-situ desorption of the adsorbent without VOCs (volatile organic compounds) accumulation. Our previous results show that the mesoporous silica gel performs well in adsorbing and desorbing the VOCs due to their capillary condensation in the mesopores. However, the microporous silica performs better in adsorbing though poorer in desorbing VOCs because of the direct interaction between VOCs molecules and the adsorbent wall in the micropores. Herein, the adsorption and desorption of o- xylene on two silica gels (SG) with different pore size distribution by vacuum swing adsorption (VSA) has been systematically studied. The equilibrium adsorption and desorption experiments of two kinds of silica gels at different loading heights in fixed bed show that the concentration front of o- xylene in microporous SG disperses slowly. However, the concentration front of o- xylene in mesoporous SG is significantly dispersed. To improve the overall efficiency of adsorption-desorption, the mesoporous and microporous SGs are loaded together in the fixed bed. It was found that the increase in the microporous SG loading percentage facilitated the adsorption capacity but deteriorated its desorption efficiency, while the opposite occurs to the mesoporous SG. After optimization, it was observed that minimal energy consumption (1.295 kWh/m 3 VOCs gas) was used when the adsorption column is loaded with 60% SG B at the inlet and 40% of the SG A at the outlet end for o- xylene vapour adsorption. This finding will be useful for designing adsorbent loading in the adsorption column.
研究领域:
化学工程
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环境科学
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
·
IF 15.1
Shuai Guo,Le-wu Zhan,Bin-dong Li
Nitration reactions are extensively studied in organic synthesis despite their notorious dangers, high reaction rates, and heterogeneous reaction systems. To date, most industrial nitration reactions rely on conventional batch reactors characterized by low mass transfer rates and limited reaction conditions. In contrast, microreactors represent a valuable technology for intensifying such nitration reactions. In this work, we established a continuous flow system of o -xylene nitration and determined the kinetics and mass transfer. The effects of mixing performance, nitric acid concentration, molar ratio, reaction temperature, and residence time on the process safety were investigated separately. The experimental data is supported by dimensionless number calculations, providing a more comprehensive understanding of the nitration reaction's transport and reaction performance in a heart-shaped microreactor. Remarkably, the residence time of the heart-shaped microreactor was reduced by an order of magnitude, while the volumetric mass transfer coefficient was improved by several orders of magnitude compared to conventional stirred tank reactors. Moreover, the spent nitric acid could be efficiently recovered and reused after concentration, further enhancing the sustainability and cost-effectiveness of the process. Our findings demonstrate the significant potential of microreactors for intensifying nitration reactions and paving the way for the design and optimization of more efficient and safer synthetic processes.
研究领域:
化学工程
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有机合成
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Zhuang Wang,Asad Mahmood,Xiaofeng Xie,Xiao Wang,Hanxun Qiu,Jing Sun
For the oxide-based photocatalysts, polyoxylic acid modification can affect their adsorption/desorption properties and further regulate photocatalytic reaction pathway, which is crucial for enhancing photocatalytic activity and selectivity. Herein, phosphoric acid modified TiO 2 was synthesized by a facile impregnation-calcination method for photocatalytic degradation of gaseous o-xylene. According to FTIR, XPS, and EDS analysis, phosphoric acid was anchored on the surface of TiO 2 successfully. The surface P atomic percentages for PT1 was 2.45%. The as-prepared phosphoric acid modified TiO 2 (PTx) had a photocatalytic performance superior to that of commercial TiO 2 and unmodified TiO 2 (PT0), with increasing by 2.2 times at most. Interestingly, the phosphoric acid molecules strongly adsorbed on anatase TiO 2 surface by forming H–O 2C and =O–Ti 5C chemical bonds according to the first principle calculations, which changed TiO 2 surface properties (specific surface area and surface negative electrostatic field) and further improved adsorption and charge carrier separation and transfer, thus improving the photocatalytic activity. Additionally, according to the intermediates results, the relative abundance of intermediates shows obvious difference. Acetone was detected as the most abundant intermediates during o-xylene degradation for PT0, whereas that was o-methyl benzaldehyde for PT1, which could be ascribed to the difference of surface adsorption configuration of o-xylene. According to the temperature-programmed desorption (TPD) results, the surface modified by phosphoric acid could change the o-xylene adsorption configuration to favor its methyl oxidation (standing configuration), whereas the unmodified surface could be more favorable to the benzene ring-open reaction (lying configuration). This work will deepen the understanding of the relevance of surface modification and surface photocatalytic reaction, which also provides a feasible strategy to improve photocatalytic selectivity.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
CHEMIE INGENIEUR TECHNIK
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2021
·
IF 1.672
Hao Guo,Zheng Wan,Yanhong Li,Xiao He,Aisheng Huang
In this study, a graphene oxide (GO) membrane is developed for the separation of p -xylene (PX, 0.58 nm) from o -xylene (OX, 0.68 nm). Attributing to the suitable d-spacing size (0.58 nm), the GO membrane allows more PX to pass through than OX, leading to a high PX/OX selectivity. At 110 °C for the separation of equimolar PX/OX mixture, the PX/OX separation factor is 9.4 and PX flux is 145.3 g m −2 h −1 , respectively, which is promising for the separation of xylene isomers by pervaporation. The separation performance of the GO membrane is further confirmed by simulation studies.
研究领域:
材料科学
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化学工程
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分离技术
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DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2023
·
IF 3.8
Wenwen Zhang,Zhigang Xue,Liyun Cui,Haoliang Gao,Di Zhao,Rongfei Zhou,Weihong Xing
The synthesis of a continuous IMF zeolite membrane was fabricated on tubular substrates by seeded growth for the first time. The straight channels of IMF zeolite with diameters of 0.53–0.59 nm are distinguishable for p -xylene from o -xylene molecules. Pure IMF-phase high-silica IM-5 zeolite seeds with uniform and fine crystal size were fabricated by a new sonication-assisted aging process. The seeds were coated on the support by dipcoating and induced the formation of continuous membrane. Separation performance in p -/ o -xylene mixture was investigated at various temperature and pressure. The typical IM-5 zeolite membrane had p -/ o -xylene separation factor of 3.7. Our results suggest that IM-5 zeolite is a potentially good membrane material for the separation of xylene mixtures.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2024
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IF 1.7
Yan Jiaqi,Fu Weiwen,You Kuiyi,Zhao Fangfang,Luo He’an
A solvent-free, acid-free, and efficient strategy was developed for the selective preparation of 4-nitro-o-xylene (4-NOX) from the catalytic nitration of o-xylene with NO 2 mediated O 2 over BiCl 3 immobilized silicic acid catalyst (BiCl 3 -SA). The results indicated that the Lewis acid BiCl 3 -SA conjoined NO 2 –O 2 as a composite system synergistically promotes o-xylene conversion and 4-NOX selectivity. Under optimal conditions, 52.4% of o-xylene conversion with 68.4% 4-NOX selectivity was obtained at 35 °C. The characterization demonstrated that the highly dispersed metal Bi species form stable chemical bonds with the SA surface, which can effectively inhibit the loss of metal species and generate abundant acid sites. The developed catalyst is not only inexpensive but also has excellent stability and catalytic performance. Furthermore, a plausible mechanism for the catalytic nitration of o-xylene using NO 2 as a nitration agent over BiCl 3 -SA was proposed. This work provides an eco-friendly and practical protocol for improving desirable 4-NOX selectivity and reducing the discharge of acidic wastewater, with potential application prospects. Graphical abstract
研究领域:
催化化学
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环境科学
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产品关联
DOI
高影响因子
FLUID PHASE EQUILIBRIA
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2021
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IF 2.775
Zhenxing Cai,Hui Zhao,Xin Zhou,Xiaobo Chen,Chaohe Yang
Solid-liquid equilibria of three binary mixtures consisting of para-xylene, ortho-xylene, meta-xylene and ethylbenzene were investigated in this study using differential scanning calorimetry (DSC) method, the mixtures were cooled to -120 °C and then heated to 20 °C at different heating rates, eutectic phase diagrams were observed for para-xylene/ortho-xylene and para-xylene/meta-xylene binary systems. The freezing point of pure ethylbenzene at atmospheric pressure is around -95 °C, but due to the effect of induction time, the observed freezing temperature is lower than -120 °C, the operation temperature of industrial xylene crystallization separation process is higher than -80 °C traditionally, therefore ethylbenzene will not crystallize in practical process, the phase diagram for para-xylene/ethylbenzene was not achieved. The experimental data were compared with data from other literatures and new features were found. The data were well correlated by Apelblat equation and λ H equation, it is significative to provide important engineering data for the separation and purification of xylene mixtures.
研究领域:
化学工程
·
热力学
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2020
·
IF 2.369
Xuemei Zhang,Xiaojie Yang,Jie Jian,Chungui Jian,Jie He,Hongwei Wang,Wangxin Kong,Guangjin Shangguan,Meifang Xia
Liquid–liquid equilibrium (LLE) data of the ternary system 2-methyl-2-butanol + water + o-xylene were determined at 303.2, 313.2, and 323.2 K under 101.3 kPa. The extraction capacity of o-xylene is expressed by selectivity, which is more than 118 and decreases with the increase of temperature. The quality of the experimental LLE data is verified by calculation of the overall mass balance and alignment between the conjugated phases and overall compositions. The experimental LLE data were regressed by the NRTL and UNIQUAC models, and the binary interaction parameters were obtained. And the root-mean-square deviations (RMSDs) are less than 1.02%.
研究领域:
化学工程
·
物理化学
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产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL ENGINEERING
·
2019
·Vol. 145
·期 10
·04019069
·
IF 1.657
Zhuowei Cheng,Xiaomin Zhang,Lichao Lu,Jianmeng Chen
Multiorganic compounds are commonly found in contaminated environments, and the utilization of pure microbial strains for their removal is inefficient. The present study was conducted to evaluate whether the use of a consortium of Aspergillus fumigatus HD2, Ophiostoma stenoceras LLC, and Zoogloea resiniphila HJ showed improved removal of a mixture of alpha (α)-pinene, n-butyl acetate, and ortho (o)-xylene in water when compared to the use of each strain. Carbon balance analysis indicated that more mineralized compounds were produced by the consortium. Microbial analysis indicated the ratio of A. fumigates and Z. resiniphila remained 1∶1, while O. stenoceras grew more slowly than the other two strains. Substrate inhibition models showed that the Levenspiel model was optimal for α-pinene and n-butyl acetate, while the Edwards model was better for o-xylene. Finally, gaseous ternary mixture removal was achieved in a continuous-flow system, indicating that this consortium would have great potential in future full-scale applications of organic treatments.
研究领域:
环境科学
·
微生物学
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DOI
高影响因子
Frontiers in Chemistry
·
2022
·
IF 5.545
Li Yongfeng,Liao Qianyan,Ling Weizhao,Ye Fan,Liu Fangfang,Zhang Xipeng,He Jiajun,Cheng Gao
Exploring high-efficiency and stable monolithic structured catalysts is vital for catalytic combustion of volatile organic compounds. Herein, we prepared a series of Pd/δ-MnO2 nanoflower arrays monolithic integrated catalysts (0.01–0.07 wt% theoretical Pd loading) via the hydrothermal growth of δ-MnO2 nanoflowers onto the honeycomb cordierite, which subsequently served as the carrier for loading the Pd nanoparticles (NPs) through the electroless plating route. Moreover, we characterized the resulting monolithic integrated catalysts in detail and evaluated their catalytic activities for toluene combustion, in comparison to the controlled samples including only Pd NPs loading and the δ-MnO2 nanoflower arrays. Amongst all the monolithic samples, the Pd/δ-MnO2 nanoflower arrays monolithic catalyst with 0.05 wt% theoretical Pd loading delivered the best catalytic performance, reaching 90% toluene conversion at 221°C at a gas hourly space velocity (GHSV) of 10,000 h−1. Moreover, this sample displayed superior catalytic activity for o-xylene combustion under a GHSV of 10,000 h−1. The monolithic sample with optimal catalytic activity also displayed excellent catalytic stability after 30 h constant reaction at 210 and 221°C.
研究领域:
环境科学
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催化材料
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化学工程
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产品关联
DOI
PubMed
高影响因子
Inorganics
·
2025
·Vol. 13
·期 8
·275
·
IF 3
Hongmei Wang,Xiaoxu Zhang,Yifei Niu,Zichuan Ma
The recovery and control of volatile organic compounds (VOCs) have gained significant attention. Supported sulfonic acid materials show potential in converting aromatic VOCs into non-volatile sulfonic acid derivatives. However, their effectiveness is closely tied to the anchoring state of the sulfonic acid groups. In this study, two supported sulfonic acids, SSA@CdO and SSA@CaO, were synthesized via the respective reactions of CdO and CaO with chlorosulfonic acid to investigate how the properties of the supports influence sulfonic acid anchoring and reactivity towardo-xylene. Comprehensive characterization and performance tests revealed that sulfonic acid groups on CdO were covalently bonded, forming positively charged sites ([O0.5Cd–O]ɗ−–SO3Hɗ+) with high loading (9.7 mmol/g), enabling excellento-xylene removal (≥95.6%) and adsorption capacity (51.67–91.59 mg/g) at 130–150 °C. In contrast, ion-paired bonding on CaO formed negatively charged sites ([O0.5Ca]+:OSO3H−), which were inactive in electrophilic sulfonation. This work provides new insights for enhancing supported sulfonic acid materials in VOC treatment.
研究领域:
环境化学
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材料科学
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催化化学
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大气污染控制
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物理化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）